Methods of storing, inserting, or managing fluids on a microfluidic chip currently rely either on an external reservoir, such as a syringe, from which the fluids may be delivered through a connecting assembly, such as a Luer adapter, or on the use of an on-chip reservoir such as a “blister pack”, similar to the macro-scale versions used for packaging and dispensing drugs. The main disadvantages of the former approach include the relatively large footprint and operational inconvenience of the devices. The disadvantages of the latter approach typically include chemical incompatibility issues with the fluids, especially if the blister pack is made of a polymer and adhesives are used to create the seal, poor hermeticity of adhesive or gasket clamping, and poor control of the method of releasing the fluid when required.
Similar considerations apply to managing materials other than fluids that may need to be encapsulated on a chip, examples including materials comprising sensitive electronics, radioactive substances, medical radioactive substances, biological agents, etc.
It is therefore desirable to provide a method for creating hermetically sealed encapsulations or chambers for materials on chips that avoids the use of polymers or adhesives, and can be easily integrated with the microfabrication techniques used to create those chips, where the bond or bonds forming the encapsulations can be conveniently and controllably opened, broken, taken apart or un-sealed, as and when required. It is additionally desirable to provide a method for achieving the controlled release or exposure of the encapsulated materials as and when required. The chips may be microfluidic chips or flow cells.
In this disclosure, the terms “open”, “break”, “take apart” “unseal”, “unbond”, “cleave” and variants thereof are used to a large extent interchangeably, and are defined as referring to the deliberate dismantling of a bond formed between two elements of the chip in question, where the dismantling may involve a break at the bond interface within the material making up the bond itself, or a break in the bulk material of one or both of the chip elements immediately adjacent to the bond interface. The word “seal” as used throughout the disclosure is defined to mean the bond joint or bond interface where two substrates are fused together, for example by a room temperature laser bonding process, or fusion welding process, or using a low temperature glass frit bonding process.